Evidence for SFA stenting proves elusive

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Twelve-month interim data presented from the Femoral Artery Stenting Trial (FAST) has concluded that Nitinol stenting is not superior to stand-alone percutaneous transluminal angioplasty (PTA) in relatively short lesions. This contrasts with data from the ABSOLUTE study which indicated that there was a benefit for SFA stenting in longer lesions.

Presented by Dr Marc Bosiers, AZ St Blasius Hospital, Dendermonde, Belgium, at the recent annual meeting of the Society for Vascular Surgery, in Philadelphia, PA, the FAST is comparing the Luminexx stent (Bard) with stand-alone PTA for the treatment of lesions in the superficial femoral artery (SFA). FAST was designed to address the poor results achieved using PTA and balloon-expandable stents in patients with SFA disease, where 12-month restenosis rates are between 40% and 50%. Previous data (eg SIROCCO) suggests that that Nitinol stents may improve mid-term restenosis rates, however, randomised trials assessing PTA vs nitinol stenting in patients with SFA lesions are lacking.Major inclusion criteria comprised a Rutherford classification of at least two, and a single de novo lesion starting minimally 1cm distal from the SFA origin with a length between 1 and 10cm by visual estimate and a degree of stenosis between 70% and 100% (also by visual estimate). The primary study endpoint was binary restenosis (at least 50% stenosis on ultrasound) at 12 months. The researchers hypothesized that stent implantation would reduce one-year binary restenosis from 45% in the PTA arm to 25%, and assumed a 15% loss-to-follow-up rate, to eventually enrol a total of 244 patients (121 randomized to PTA, 123 to stent). Except for a lower prevalence of males in the stent arm (63% vs. 75%), pertinent patient characteristics were well matched between the study arms. Crossover from the PTA arm to the stent arm became necessary in 13 patients.

At six months the results demonstrated binary restenosis rates (as determined by Doppler ultrasound) of 25.5% in those treated with the Nitinol stent vs 38.3% in patients who underwent angioplasty. The 33% reduction did not achieve statistical significance in the intent-to-treat analysis, but the results of the per-protocol analysis, which included 13 patients who crossed from one arm to the other because they required both angioplasty and stenting, were significant (P=.085). Moreover, re-intervention rates also favoured stenting, with 12.4% (15/121 patients) of those patients in the PTA group undergoing revascularisation, compared to 6.5% (8/123 patients) in the stenting group. Ankle-brachial index improved by 0.12 in the stent group vs. 0.18 in the angioplasty group, a statistically significant difference.

Bosiers said the 12-month interim results from 214 patients did not match the six-month results. The interim results indicated that primary SFA stenting is not superior to stand-alone PTA in relatively short lesions (average length 44mm). However, he added that any conclusions must wait until a definite 12-month analysis of all 244 patients can be made.

In a subsequent presentation, results from the aSpire Registry determined that although the use of the aSpire (Vascular Architects) nitinol self-expandable polytetrafluoroethylene (PTFE) covered stent for the treatment of long lesions of the superficial femoral arteries (SFAs) is safe, the results were disappointing due to the high number of reinterventions necessary in order to obtain an optimal assisted primary patency.

The prospective multi-centre registry was designed to evaluate safety, effectiveness and patency of self-expanding PTFE covered stent in patients with femoro-popliteal occlusive disease. The aSpire Registry included 152 patients (168 limbs) enrolled in 16 centres during a 15-month period (2003-2004) for medium/long (>3cm) occlusion (N=118) or stenosis (N=50) of the SFA (N=53) or of the proximal popliteal (N=115) arteries. Dr Massimo Lenti, from the vascular surgery unit of the University of Perugia, Italy, and his co-authors evaluated the results of 168 limbs for lesions of more than 3cm. Ninety-two procedures were performed for intermittent claudication, 34 for rest pain and 42 for limb savage (five ended in amputation).

The mean length of vessels segments covered was 104.35mm + 73.7. Indications for treatment included 44 Type B1, 57 type B2, and 67 Type C1 lesions according to TASC classification. Follow-up including clinical and ultrasound evaluation were performed at discharge at one, six and 12 months and yearly thereafter. Mean follow-up was ten month (range 1-27). Primary end-points were immediate technical success (vessel recanalization with residual stenosis <30%) and stent patency. Presenting the results, Lenti said 25 patients suffered complications from the procedure including six peripheral embolizations, seven thromboses, three hemorrhages, two vessel ruptures and seven vessel dissections. Lenti added that 31 reinterventions (frequently percutaneous) had to be performed to attain an optimal assisted primary patency. Sixteen cases were managed with a catheter, while 15 patients had to have surgery. Initial technical success was obtained in 162/168 procedures (96.4%). In 39 procedures more than one stent was applied resulting in a total of 216 stents. In 99 cases femoral surgical access and in 11 debulking techniques were employed to obtain stent placement. Life table estimates of primary patency at 12, 18 and 24 months were 64%, 60% and 57%, respectively. Assisted primary patency rates at 12, 18, and 24 months were 76%, 74% and 71%, respectively. Amputation was required in 5/42 patients treated for limb salvage. At multivariate analysis critical limb ischaemia was the only significant predictor of late failure. “Longer lesions (of more than 3cm) are often found in patients with femoro-popliteal obstruction,” said Lenti. “Endovascular therapy with this particular stent has the potential to improve symptoms and the quality of life to prevent limb amputation. These are mid-term results, so although use of the aSpire stent appears to be safe, further evaluation of clinical outcomes at a longer follow-up, as well as technological and pharmalogical improvements, are warranted to better define the applications of the device,” said Dr. Lenti.

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